The present invention is related to Japanese patent application No. Hei. 11-200894, filed Jul. 14, 1999; the contents of which are incorporated herein by reference.
The present invention relates to a residual pressure elimination structure of a sealed container, and more particularly, to a residual pressure elimination structure of a sealed container which allows the inside to be completely closed from the outside and returns only cooling water to an engine cooling water system.
Conventionally, as shown in FIG. 12, a sealed reserve tank 100 for returning only cooling water to an engine cooling water system, separates air inside the engine cooling water system from the cooling water. The tank is connected, in a fluid-tight manner, to a radiator through a connection pipe (not shown). In addition, the sealed reserve tank 100 is also connected in a fluid-tight manner between a water pump 97 of a water-cooling-type engine 96 and a thermostat 98 by a connection pipe 99.
As shown in FIG. 13, there is a first conventional sealed reserve tank 100 which comprises a resin tank main body 101 shaped as a container and having a resin screw cap 102 screwed over an injection port 103 of the resin tank main body 101. The resin tank main body 101 has an inner cylindrical wall 104 surrounding the injection port 103 and an outer circumferential screw portion 105 formed on the outer circumference of the inner cylindrical wall 104. The inner cylindrical wall 104 is also referred to as a neck filler or a seal portion.
On the other hand, the resin screw cap 102 has a valve case 106, a handle 107 having a cylindrical shape, an inner circumferential screw portion 108 and a disc-like gasket 110. In the valve case 106, a pressure control valve and a negative pressure valve are disposed. The cylindrical handle 107 is provided on the outer side of the valve case 106. The inner-circumferential screw portion 108 is formed on the inner side of the cylindrical handle 107 and screwed up or down using the outer-circumferential screw portion 105. The gasket 110 is attached to a lower-end surface of a flanged portion 109 of the valve case 106.
Another typical sealed tank, illustrated in FIG. 14, includes a second conventional sealed tank 200 which comprises a resin tank main body 201 shaped as a container and having a resin screw cap 202 screwed over an injection port 203 of the resin tank main body 201. The resin tank main body 201 has an inner cylindrical wall 204 surrounding the injection port 203, an outer cylindrical wall 206 separated from the inner cylindrical wall 204 (seal portion) in a radial direction by cylindrical gap 205, an inner circumferential screw portion 207 formed on the inner circumference of the outer cylindrical wall 206 and an overflow path 208 for discharging cooling water from the lower end of the wall 206 to the outside.
Resin screw cap 202 has a valve case 209, an outer wall portion 210, an outer circumferential screw portion 211 and a disc-like gasket 213. In the valve case 209, a pressure control valve and a negative pressure valve are disposed. The outer wall portion 210 is provided on the outer side of the valve case 209. The outer circumferential screw portion 211 is formed on the outer side of the outer wall portion 210 and screwed with the inner circumferential screw portion 207. The disc-like gasket 213 is attached to an annular mounting groove 212 formed on the outer circumference of the valve case 209.
In the first conventional sealed reserve tank 100, shown in FIG. 12, when the resin screw cap 102 is loosened to replace cooling water, the cooling water leaks through a seal portion between the inner cylindrical wall 104 of the resin tank main body 101 and the gasket 110 as shown in FIG. 13. This leakage occurs from the engine cooling water system wherein the cooling water is at a high temperature and at a high pressure. The leaking cooling water then flows to a shoulder portion 111 of the resin tank main body 101 through a gap between the outer-circumferential screw portion 105 and the inner-circumferential screw portion 108.
Thus, when the resin screw cap 102 is removed from the resin tank main body 101, the cooling water is dispersed over portions surrounding the resin screw cap 102 or over the upper surface of the shoulder portion 111 of the resin tank main body 101. It is therefore possible that the high-temperature cooling water splashes on the service person, jeprodizing safety. In addition, since the cooling water is randomly dispersed around resin screw cap 102, the surface of the resin tank main body 101 becomes dirty, thereby reducing appearance. Therefore, the user, who sees the dirt on the surface of the resin tank main body 101, assumes that cooling water has leaked from the sealed reserve tank 100 due to some damage, leading the user to believe the reliability of cooling-water replacement or product is poor.
In the reserve tank 200, when the resin screw cap 202 is loosened to replace cooling water, the cooling water leaks through a seal portion between the inner cylindrical wall 204 of the resin tank main body 201 and the gasket 213 as shown in FIG. 14. Again, this leakage is from the engine cooling water system wherein the cooling water is at a high temperature and high pressure. Since leaking cooling water then flows out through an overflow path 208 in a specific direction, the appearance of the second conventional sealed reserve tank 200 is good in comparison with the first conventional sealed reserve tank 100.
However, the position at which the gasket 213 is removed from the inner cylindrical wall 204 is higher than the lower-end position of the outer circumferential screw portion 211 of the resin screw cap 202. As shown in the figure, the removal position of the gasket 213 from the inner cylindrical wall 204 is higher than the lower-end position of the outer circumferential screw portion 211 of the resin screw cap 202. Thus, when a large amount of high-temperature and high-pressure cooling water overflows from the engine cooling water system, the cooling water flows through a gap between the outer circumferential screw portion 211 and the inner circumferential screw portion 207 of the resin tank main body 201, leaking from the portions surrounding the resin screw cap 202 to the upper surface of the resin tank main body 201. The present invention was developed in light of these and other drawbacks.
To address the aforementioned drawbacks, the present invention provides a seal portion mounted on an inner wall of a cap. When the cap is removed from the main body of the container, the seal is positioned below a position where a first screw thread is screwed to a second screw thread. The first screw thread is formed on inside or outside of an outer cylindrical wall of the main body of the container. Whereas, the second screw portion is formed on the outer circumference or the inner circumference of the outer wall portion of the cap.
In this configuration, when the cap is removed from the main body of the container during high fluid temperature and pressures, fluid leaking out from the gap between the seal portion and the inner cylindrical wall or the inner wall does not leak out from a gap between the first screw portion of the main body of the container and the second screw portion of the cap. Instead, it is discharged in a specific direction toward the outside of the main body of the container from a position lower than the first screw portion through an overflow path. Since dirt on the surface of the main body of the container can be avoided without putting the safety of the service person at stake due to dispersing high-temperature fluid over portions surrounding the cap, the safety of the service person, the appearance of the container and the reliability of the service work can be maintained in a good state.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.